DNS 06: A Forwarding Resolver

The concierge who does not know the answer and walks the directory for you. A forwarder is the concierge who instead phones a bigger concierge, and passes on what they say.

Before you start. DNS 05: Compressed Names taught the server to read names written as pointers, and gave it a small client that decodes any reply. Until now the server answered only for the names in its own map, and said NXDOMAIN for everything else, even www.github.com. A resolver is a server that finds answers for names it does not own. A forwarder is the simplest kind: it asks one bigger resolver and relays the reply. This lesson builds it, and the result is a server you could set as your computer’s DNS.